A liquid crystal display device is used in various fields of OA equipments such as a personal computer and a television set, taking advantage of the features such as light weight, thin shape, and low power consumption. In recent years, the liquid crystal display device is used also as displays for a portable remote terminal such as a cellular phone and PDA (personal digital assistant), a car navigation equipment, and a game machine.
In the liquid crystal display device, it is important to form a uniform cell gap, i.e., a uniform thickness of the liquid crystal layer held between a pair of substrates in an active area displaying images. In recent years, while selectively arranging pillar-shaped spacers on one substrate as a spacer for forming the cell gap, technology to form the spacer with sufficient accuracy in height is established, and the uniform cell gap is attained.
There is One Drop Fill (ODF) method as one of the technology for manufacturing the liquid crystal display device. According to the ODF method, an array substrate and a counter substrate are pasted together in a vacuum state after dropping liquid crystal materials in a region surrounded with a seal material on the array substrate or the counter substrate. In this method, the pair of substrates is pressed by a difference in the pressure between an inner region surrounded with the seal material and outside by returning to an atmospheric pressure state from the vacuum state, and the seal material is crushed. Thereby, a predetermined cell gap is formed. As the seal material applied to the One Drop Fill ODF method, ultraviolet curing type adhesives are used widely. However, since viscosity is high, the system which draws the seal material using a dispenser is adopted not by a printing method. The above ODF method has advantages, such as improvement in shortening of tact time, and efficient use of the material.
In recent years, in order to improve response characteristic, alignment characteristic, viewing angle characteristic, etc., of the liquid crystal display device, there is a tendency which narrows the cell gap. Moreover, request for reducing the external form size of the liquid crystal display device is increasing, and there is a tendency for the width of the seal material to become narrow according to the narrow frame. Such formation of the narrow cell gap and narrow frame results in reduction in the amount of application of the seal material.
The low amount application of the seal material is achieved by adjusting the pressure for extruding the seal material and the speed for drawing the seal material, etc. However, variation in the applied amount of the seal material is generated depending on the stability (circumference temperature) of the viscosity of the seal material because high velocity material is used. Furthermore, a defect such as a pattern cut is easily resulted in the process of the drawing due to a filler contained in the seal material.